Yes, this is similar to the first point; however, it's important to take this one step further. Don't just stop at “best sleeping bags” or “sleeping bag reviews”! You should target phrases that are even longer tailed, which could mean going after keywords with very low search volume. I do that here on Niche Pursuits and every blog or website I've built.
In April 2008 the State of New York inserted an item in the state budget asserting sales tax jurisdiction over Amazon.com sales to residents of New York, based on the existence of affiliate links from New York–based websites to Amazon. The state asserts that even one such affiliate constitutes Amazon having a business presence in the state, and is sufficient to allow New York to tax all Amazon sales to state residents. Amazon challenged the amendment and lost at the trial level in January 2009. The case is currently making its way through the New York appeals courts.
Affiliate marketing is commonly confused with referral marketing, as both forms of marketing use third parties to drive sales to the retailer. The two forms of marketing are differentiated, however, in how they drive sales, where affiliate marketing relies purely on financial motivations, while referral marketing relies more on trust and personal relationships.